Matrix sorter system with transpositor conveyor

ABSTRACT

A matrix conveying system for intended use in sorting articles and related methods of conveying and sorting articles are disclosed. In one embodiment, the matrix system comprises a plurality of first conveyors extending in a first direction and a plurality of second conveyors extending in a second direction, each intersecting the plurality of first conveyors. A transfer conveyor, such as a transpositor conveyor, may be provided for transferring articles from one of the first conveyors to one of the second conveyors. The system may be used to sort articles delivered from one or more storage locations for distribution, or may instead be used to sort articles for delivery to one or more storage locations.

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/059,523 filed Jun. 6, 2008, the disclosure ofwhich is incorporated herein by reference. This application is acontinuation-in-part of Ser. No. 11/568,478 filed Oct. 30, 2006, nowU.S. Pat. No. 8,113,334, which claims the benefit of internationalapplication PCT/US05/14970 filed Apr. 28, 2005, which claims the benefitof U.S. Provisional Patent Application Ser. No. 60/567,411 filed Apr.29, 2004 and Ser. No. 60/618,853 filed Oct. 14, 2004, the disclosures ofwhich are all incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to the article conveying art and, inparticular, to a system including a matrix of conveyors for conveying orsorting articles.

BACKGROUND OF THE INVENTION

Over the past several years, the demand from businesses and individualsalike for second day and even overnight deliveries of articles, such assmall to mid-sized parcels, packages and letters, has steadilyincreased. This demand is due, in part, to the prevalence of Internetand mail order shopping, which creates a similar need for an efficientand effective distribution system to deliver expediently the wares to acommon carrier. Consequently, the need for methods and systems forquickly transporting, sorting and distributing this ever increasingvolume of articles has similarly increased.

In fact, it is now general practice for common carriers to transportarticles in the form of small to mid-sized packages or the like to acentral sorting terminal or hub, where they are sorted according toselected parameters, such as having common regional destinations, andthen delivered as a group. Once these destinations are reached, it isnecessary to sort again to distribute articles in the group to theirfinal destinations. To accomplish these tasks in the amount of timerequired to insure overnight delivery, the central as well as theregional sorting terminals or hubs must receive, sort and distributehundreds of thousands of coded packages each day. Besides on thedelivery side, a similar need exists on the distribution side, sincepurchasers have become accustomed to receiving ordered items withoutsignificant delay.

Necessarily, the sortation systems used must be capable of processingthe packages within these defined time parameters. Indeed, in responseto the continuously increasing number of packages requiring next day orovernight delivery, the sortation systems must operate much faster andmore efficiently than just a few years ago. It is also desirable for thesystems to be more adaptable to accommodate fluctuations in need/demand,as well as simpler and less expensive.

Since as early as the 1960's, various package sortation systems haverelied upon primitive “induction” type systems including an endless“loop” conveyor with mobile units that receive, transport and depositpackages at selected distribution stations. Specifically, U.S. Pat. Nos.3,167,192 to Harrison et al. and 3,327,836 to Burt each disclose packagesortation systems using tilt tray assembly units propelled by an endlessconveyor chain. Timers and somewhat unreliable magnetic readers actuatetip solenoids to tilt the trays to one side, thus in theory allowinggravity to pull passively the packages from atop the trays upon reachingtheir destination. As should be appreciated, the speed with which such asystem can process articles leaves much to be desired, especially sincearticles must potentially traverse the entire loop before reaching thedesired destination.

A more recent sortation system described in U.S. Pat. No. 4,832,204 toHandy et al. integrates these prior art tilt tray sortation systems withmore complicated scanning equipment and computer control in an attemptto improve overall system speed and efficiency. Despite the successfulintegration of these components into a supposedly more modern and stateof the art system, and at a cost of much greater complexity and cost,the system of the '204 patent still fails to improve the basic sortationapparatus and methods. In essence, package delivery customers arecalling for a move away from the continued reliance on the complex andexpensive tilt tray systems that rely primarily on gravity transfer,such as in the '204 patent, and at the same time demanding significantincreases in the overall speed, efficiency and adaptability of thesortation system.

In recent times, “tilt tray” sorters have been replaced by allegedlymore efficient “cross belt” sorters. One version of this type ofsortation system includes an endless train of driven cars passoperator-controlled feed conveyors used to deliver a single article fortransport around the loop. When the car reaches the desired destinationfor the article, an onboard conveyor actuates to eject the article to atakeaway conveyor. An early example of this type of system appears inU.S. Pat. No. 3,977,513 to Rushforth, and a more modern example appearsin the September 2003 issue of Modern Material Handling magazine (whichis incorporated herein by reference).

Despite the industry-wide movement toward this type of sorting system,it still suffers from similar problems with efficiency. Just like in thetilt tray systems, only a single article can be loaded onto a selectedcar at a given instant in time. This serves as a significant limitationon the total throughput possible, and requires operating many suchsystems simultaneously to keep up with the demand. The use of individualcars with cross belts, which are typically complicated in construction,also presents problems from a reliability and maintenance standpoint.

Furthermore, past sortation systems cannot sort articles continuously,since various events demand downtime. For example, articles sometimesmis-introduced into the system must be retrieved and removed. Likewise,completing the previous sorting operation before introducing the nextgroup of articles requires introducing any articles accidentally leftout from the previous operation, which results in costly downtime.Running two induction-type sortation systems in parallel alleviates theproblem in part, but this will not necessarily reduce the cost. Theexisting systems also tend to occupy a great deal of floor space, whichmay make this impossible to accomplish using a given facility.

Thus, an important aspect of the effort to improve this technologyinvolves providing a sortation system and related method capable oftransporting, sorting and distributing the increasing volume of sucharticles in a more efficient manner. Increased efficiency andadaptability of use, as well as lower cost and maintenance, shouldadvantageously result without a concomitant increase in complexity.

SUMMARY OF THE INVENTION

One aspect of the disclose relates to a conveyor system for intended usein conjunction with the sorting of articles. The system comprises aplurality of first substantially continuous conveyors extending in afirst direction, each providing a first conveying surface for thearticles. The system further comprises a plurality of secondsubstantially continuous conveyors extending in a second direction andintersecting the first conveyors, each second conveyor providing asecond conveying surface for any articles transferred from one or moreof the intersecting first conveyors. Means for transferring at least onearticle from at least one of the first conveyors to an intersecting oneof the second conveyors is also provided.

In one embodiment, the means for transferring comprises a transpositorconveyor. Preferably, the transpositor conveyor comprises a portion ofat least one of the first conveyors, and most preferably overlies thesecond conveying surface at an intersection with at least one secondconveyor. The transpositor conveyor comprises a retractable section,which may be positioned at least partially within a housing of thetranspositor conveyor in a retracted condition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially cutaway plan view of the sortation system formingone aspect of the invention;

FIG. 2 is a partially cutaway side view of the system of FIG. 1;

FIG. 3 is a partially cutaway side view of a takeaway conveyorassociated with the system of FIG. 1;

FIG. 4 is a perspective view showing another embodiment of the sortationsystem;

FIG. 5 is a partially cutaway top plan view of one embodiment of asub-sorting station;

FIG. 6 is a partially cutaway perspective view of a sub-sorting station;

FIG. 7 is a partially cutaway plan view of yet another embodiment of thesortation system, including three levels of conveyors;

FIG. 8 is an end view of two of the conveyors forming part of the systemof FIG. 7;

FIG. 9 is a partially cutaway side schematic view of one possible meansfor transferring articles between two conveyors;

FIG. 10 is a partially cutaway top plan view of a transferring meanssimilar to the one shown in FIG. 9; and

FIGS. 11-18 illustrate a further embodiment of a sortation systemincluding the details of a transpositor conveyor as a transferringmeans.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, one possible embodiment of a sorter system 10forming one aspect of the invention is schematically illustrated. Asillustrated, the sorter system 10 may comprise a “matrix” formed of aplurality of intersecting belt or chain conveyors 12, 14 extending indifferent directions. Each conveyor 12, 14 is of the endless belt orchain type, and thus provides a substantially continuous conveyingsurface for articles (as contrasted from tilt tray sorters, which unlikebelt or chain conveyors create a substantially interrupted conveyingsurface). Although certainly not a requirement, a preference exists forthe types of endless belt or chain conveyors manufactured and sold bySpan Tech, LLC under THE DESIGNER SYSTEM® trademark, the details ofwhich are found in U.S. Pat. Nos. 4,953,693 and 5,031,757 (which areincorporated herein by reference).

As a result of this arrangement, each intersection represents a possibleor potential location or point T for transferring an article between theassociated conveyors 12, 14. Consequently, two or more selected articlesconveyed along different infeed conveyors 12 extending in one directionmay undergo simultaneous sortation and delivery to one or more of thetakeaway conveyors 14 extending in a different direction and associatedwith a particular destination (such as a delivery truck, receiver, orsortation subsystem). By creating a system 10 including numerous infeedand takeaway conveyors 12, 14 extending in both directions andselectively moving articles between them at the desired intersections,article sortation can thus be achieved in a highly efficient andeffective manner, and one heretofore unknown using prior types ofendless loop induction systems.

In the embodiment shown in FIG. 1, the infeed and takeaway conveyors 12,14 of the system 10 extend generally perpendicular to each other (notefirst and second orthogonal directions D₁ and D₂) in a spaced apartfashion and thus form a “regular” grid (e.g., 4×4, although an irregulargrid (2×3, 4×5, 40×50, etc.) could easily be used as well). In thisparticular illustrated embodiment, the matrix system 10 comprises: (1) afirst set or series of infeed belt or chain conveyors 12 a-12 nextending in a first longitudinal direction (four conveyors shown,labeled 12 a-12 d); and (2) a second set or series of takeaway belt orchain conveyors 14 a-14 n extending in a second longitudinal directiontransverse to the first direction (four shown, labeled 14 a-14 d). Theseinfeed and takeaway conveyors 12, 14 preferably each associate with adistinct starting point S and ending point E (i.e., they are linear orstraight and independent from each other, as contrasted with known priorart induction systems using an endless loop conveyor with a continuoustrain of cars to effect sortation). Preferably, the conveyors 12, 14 ineach series extend generally parallel to each other, including in theportion comprising the system 10, and move in the same direction (notearrows A and B in FIG. 1) along an endless path.

As perhaps best shown in FIG. 2, the infeed conveyors 12 a-12 dgenerally lie in a first horizontal plane above the secondary ortakeaway conveyors 14 a-14 d, which are in a second, differenthorizontal plane. This provides the system 10 with multiple layers,levels, or tiers of conveyors 12, 14. In one proposed embodiment, theinfeed conveyors 12 a-12 d all lie above the takeaway conveyors 14 a-14d. However, as indicated in the description that follows, thisarrangement may be reversed or, alternatively, more than two layers ofintersecting conveyors may be used, with shown above and some below eachother (see FIG. 7). Although not shown, it should be appreciated thatthe conveyors 12, 14 are all preferably supported above the ground, suchas in the manner disclosed in the '693 or '757 patents.

In accordance with another aspect of the invention, means fortransferring at least one selected article between the conveyors may beprovided at or near each intersection between an infeed conveyor 12 anda takeaway conveyor 14. In the embodiment of FIG. 1, the means fortransferring comprises a transfer conveyor 16. The transfer conveyor 16may comprise a generally L-shaped, driven, endless belt or chainconveyor, oriented such that the articles transferred onto it move fromthe plane of the corresponding infeed or first conveyor, such asconveyor 12 a, to the corresponding takeaway or second conveyor, such asconveyor 14 a. The use of an L-shaped transfer conveyor 16 asillustrated is especially preferred in situations where the articleshave a direction of elongation, since the article upon reaching thetakeaway conveyor 16 will normally assume the exact same orientation ithad on the infeed conveyor 12 (which may have been selected by theperson placing the articles to ensure that an indicia such as a bar codewas in a proper position for being read). However, the use of a linearor passive transfer conveyor 16, such as for example, a straight endlessconveyor or a passive slide/chute, is also possible.

To move one or more of the articles selected for transfer onto theconveyor 16, a diverter 18 may be used. The diverter 18 functions todivert or move a selected article onto the transfer conveyor 16, and maythus comprise any structure for performing this function. For example,the diverter 18 may comprise a retractable arm, gate, lug, or guide formoving into the path of a selected article on the associated infeedconveyor 12 and directing it onto the transfer conveyor 16.Alternatively, the diverter 18 may comprise a picker, kicker, pusher, orlike motive device.

As should be appreciated from the foregoing, the particular means usedto move any selected article between the conveyors 12, 14 could varydepending on the arrangement used and any special needs (e.g., conveyingdelicate articles versus books). Likewise, instead of an active transferconveyor 16, the transferring means for example may comprise a pusher,kicker, ejector, lifter, elevator, actuator or combinations thereof fortransferring an article from one conveyor to another, including inpossible combination with a chute or conveyor. Although not preferred,the possibility of using a manual “pick and place” operation at eachintersection exists (which especially helps when one or more of thetakeaway conveyors are above the infeed conveyors). In any case,selected articles reliably make their way from the infeed conveyors 12to at least one of the takeaway or secondary conveyors 14, therebyeffecting the desired sortation.

Turning back to FIG. 2, the portion or leg of the L-shaped transferconveyor 16 adjacent to and generally aligned with the takeaway conveyor14 a may be tilted relative to a horizontal plane. Advantageously, thistilting may cause an article being conveyed along the transfer conveyor16 to slide automatically onto the associated takeaway conveyor 14without the need for active engagement. A passive diverter (not shown),such as a fixed gate, may also be provided at or near the end of thisleg of the transfer conveyor 16 to help insure that any articles that donot slide off are ultimately diverted. However, instead of a tiltedarrangement with a passive diverter, it is also possible to provide anactive diverter (not shown) for moving articles from a non-tiltedsection of the conveyor 16.

In order to insure that proper selection for transfer is achieved (andthus sorting provided), articles approaching on the infeed conveyor 12may be identified visually by an operator or using well-known types of“machine vision” scanning technology (e.g., reading a bar or other codeusing an adjacent (preferably overhead) reader 20)). Preferably, thearticle spacing on each infeed conveyor 12 is such that only oneselected article is transferred at a time. However, unlike in priorsystems utilizing tilt trays running in endless loops in which only asingle article may be processed at a given instant in time, articles fordelivery to common destinations may simultaneously transfer fromdifferent infeed conveyors 12 a-12 d to one or more of the takeawayconveyors 14 a-14 d. More efficient sorting operation and a potentialmulti-fold increase in throughput without a concomitant increase inconveying speed results.

In the case where all articles divert or transfer onto takeawayconveyors 14 a-14 n, then the infeed conveyors 12 a-12 n may simplyterminate. However, an alternative approach extends one or more of theinfeed conveyors 12 a-12 n such that articles not transferred ultimatelyreach a downstream location for further processing. For example, anarticle remaining on one infeed conveyor 12 a, such as the result ofinadvertent placement, and not actually needed to fill an order made(and thus not transferred to any of the takeaway conveyors 14 a-14 n),may reach a “reject” bin (not shown). Alternatively, such articles maycollect on a single return conveyor (not shown) extending back to anassociated storage area.

Another alternative involves delivering the articles remaining on theinfeed conveyors 12 a-12 n to another sorter system, including possiblyanother matrix system (not shown). In the latter case, a “single row”matrix may include a single endless belt or chain infeed conveyor havinga continuous conveying surface and a plurality of takeaway conveyorsintersecting this infeed conveyor. This arrangement may work well insituations where the articles are all intended for delivery to differentaddresses in the same city or zip code or otherwise share a commoncharacteristic.

Turning to FIG. 3, each takeaway conveyor 14 a . . . 14 n in the system10 may also orient at an angle, or “tilt,” relative to the horizontalplane in a direction transverse to the conveying direction, either atthe transfer point or at a downstream location. Such tilting causestransferred articles to slide down along the corresponding conveyingsurface to a known edge, which may be defined by a side guard (notshown) adjacent to the associated takeaway conveyor 14. As should beappreciated, this tilting generally turns the articles to achieve aparticular orientation (e.g., short end leading, in the case of anelongate article) for a desired operation (e.g., reading a bar code,such as using an adjacent reader 20). Once the operation is complete, itmay also be desirable as shown in FIG. 3 to provide a portion of theconveyor 14 with a “twist” section 22 that returns the article to aposition parallel with a horizontal plane before undergoing furtherprocessing.

Exemplary uses of the matrix sorter system 10 described above aremyriad. One such use involves a facility for delivering articles such asbooks from a storage location in a warehouse to a particular destination(such as to a packaging area or loading dock for shipping to retailstores). In particular, each infeed conveyor 12 associates with agrouping of books within the warehouse. A “pick to light” systemvisually identifies to a “picker” the books at the storage location inthe warehouse (such as an adjacent shelf or pallet) to place on theinfeed conveyor 12. Pickers may thus place individual books on differentinfeed conveyors 12 running in parallel or alternatively on a singleconveyor that ultimately divides into several infeed conveyorsassociated with the system 10.

In either case, the books on each infeed conveyor 12 a . . . 12 n uponapproaching the system 10 undergo identification, either by an operatoror a machine scan (in which case, a person positioned upstream of thescanning location may ensure the books are in the proper orientation andsingulated (e.g., separated by a certain minimum distance in theconveying direction)). Each takeaway conveyor 14 may be associated witha common parameter or characteristic shared by some books (e.g., thosegoing to a particular destination, company/individual, distributioncenter, store, sorting location, etc.). Once identified, thecorresponding books on the various infeed conveyors 12 are identifiedand then transferred to the correct takeaway conveyor 14 to effectsortation in the desired fashion using the above-described transfertechniques (which, again, are preferably automated, but may instead bemanual or semi-automated).

Downstream along the takeaway conveyor 14, the books may undergo furthersorting, if necessary (such as if those having different destinationsare transferred). Of course, placing persons along this conveyor 14 toidentify and move the books to packages, bins, bags, carriers, etc.works for this purpose. Alternatively, and as discussed further below,this “sub” sorting may instead use an automated system, such as one thatdetects and routes each book to an appropriate takeaway conveyor fordelivery to a receiver (e.g., bag, box or bin) representing an order.

An example of a particular sub-sorting arrangement useful with a matrixsorter system 10 essentially as described above is shown in FIGS. 4-6.FIG. 4 shows that the overall system 10 comprises a plurality (twenty)infeed conveyors 12 extending in a first direction and a plurality (ten)of takeaway conveyors 14 extending in a second direction. The takeawayconveyors 14 generally lie in a common horizontal plane, but arepositioned below the infeed conveyors 12. Each of the ten takeawayconveyors 14 associates with one or more sortation “stations” 24. In theillustrated embodiment, three such stations 24 a, 24 b, 24 c lie spacedfrom each other in the conveying direction and on the same side of acommon takeaway conveyor 14 (which it should be appreciated may be adistinct conveyor from the one forming part of the basic system 10).

Turning to FIGS. 5 and 6, it can be seen that each station 24 comprisesat least one and preferably a plurality of transverse conveyors 26 fordelivering the articles from the associated takeaway conveyor 14 to atemporary storage location corresponding to articles sharing a commoncharacteristic (e.g., those comprising a particular order, or thosegoing to a particular country, region, state, zip code, city, town,village, address, etc.). In the embodiment shown, six such substantiallycontinuous conveyors 26 a-26 f extend in parallel. Preferably, eachconveyor 26 a-26 f comprises an “indexing” conveyor including aplurality of individual conveyor segments arranged in series (with sixsegments 28 a-28 f shown for purposes of illustration only), whichtogether define each continuous conveyor. A common electric motor (notshown) may drive these segments 28 a-28 f at the same speed and in thesame direction, or alternatively separately actuated motors may drivethem independent of each other. As indicated in FIG. 5, a selectedarticle may be transferred to the leading segment 28 f of each indexingconveyor 26 a-26 f from the takeaway conveyor 14 using an associateddiverter 18.

A sensor (not shown) associated with each conveyor segment 28 a-28 f maydetect the presence of an article thereon. A conventional “photoeye”arrangement or mechanical type sensor (e.g., a weight sensor, a physicalcontact switch, etc.) may serve in this role. Upon an articletransferring from the takeaway conveyor 14 to one of the indexingconveyors 26 a-26 f, the corresponding segments 28 a-28 f run until thesensor associated with the segment 28 a closest to the storage location,or bin 30, detects the article.

In the event a second article for delivery to a second location or bin30 reaches that same indexing conveyor 26 a-26 f that article transfersin a similar fashion. The second article conveys until it reaches thesegment 28 b upstream of the segment 28 a holding the first article,which may be held stationary. This sequence can be repeated until anarticle associates with each segment 28 a-28 f of each indexing conveyor26 a-26 f.

Once one or more of the indexing conveyors 26 a-26 f are loaded, thearticles transfer to the appropriate storage location. In theillustrated embodiment, this comprises a structure 30 including aplurality of bins 32 arranged in columns corresponding to the number ofindexing conveyors 26 a-26 f. The number of rows may be as few as one(in which case the indexing conveyor described above could be replacedwith a simple continuously running conveyor for transferring selectedarticle(s) from the takeaway conveyor 14 to the appropriate bin).However, to maximize the throughput, the number of bins preferablycorresponds at least to the number of segments on the associatedindexing conveyor, and most preferably to the number of segments 28times the number of conveyors 26. Thus, in the example where sixindexing conveyors comprise six segments each, the structure 30 is sixbins by six bins.

The outfeed end of each indexing conveyor 26 a-26 f nominally liesadjacent only one row of bins 32. If any article on the farthestdownstream indexing conveyor 26 a-26 f belongs in one of those bins(which may be known using either on the spot detection (manual orautomatic) or controls), then the corresponding indexing conveyoractuates such that the article transfers to the desired bin. Thenext-in-line article then advances as described above until the sensorassociated with the furthest downstream segment (segment 28 a in theexample) detects the article. If that article belongs in the same bin asthe preceding one (such as if both are going to a common destination orotherwise share a common characteristic), then it too transfers.

Once all articles slated for a bin in the nominal row transfer, thestructure 30 may be moved to associate the bins of another row with theoutfeed end of the indexing conveyors 26 a-26 f, and the sequencedescribed above repeats. In the case where the bins 32 are spaced bothhorizontally and vertically from each other, this may be accomplished byusing a lifter to raise and lower the structure 30 such that an articleto be transferred from the furthest downstream segment 28 a of eachindexing conveyor 26 a-26 f positioned adjacent the correct bin, atwhich time that segment activates to effect delivery. Alternatively, thetransverse conveyors 26 may move to associate with the correct bins 32.

As illustrated, the structure 30 may be mobile, such as through theprovision of wheels 34. Once sortation ends for a given run or shift,the structure 30 may move to a location where the articles are furtherprocessed (such as for packaging). In the interim, a replacementstructure may be associated with the station 24 such that the sortationefficiency remains unhindered because of the time required to check andunload the bins.

As noted above, each structure 30 in the arrangement shown in FIGS. 4-6thus includes thirty-six bins. In this exemplary arrangement, threestructures 30 associate with each takeaway conveyor 14, and ten takeawayconveyors exist. The total number of possible sort destinations equals1,080. If the twelve rows of bins exist instead of six, this figuredoubles and thus becomes 2,160. If six stations associate with eachsecondary conveyor, it doubles again to 4,320. Then doubling the numberof takeaway conveyors (including by possibly adding a third level ofconveyors; see below) to twenty results in 8,640 possible sortaddresses, a figure unheard of using a conventional single inductionloop of any reasonable size.

An alternative to a vertical arrangement is one where the structure 30shown in FIG. 6 lies with its back 30 a parallel to the ground such thatthe bin entrances 32 a are positioned below the indexing conveyors 26a-26 f. A linear motion device could then move the structure 30 to andfro as necessary to ensure that the articles transferred from thesegments fall into the appropriate bin. Likewise, providing fewer rowsthan the number of indexing conveyors makes it necessary to move thestructure 30 in two different directions to match the next-in-linearticle with the corresponding bin.

Instead of using the arrangement shown in FIGS. 5 and 6, yet anotheroption involves accomplishing further sorting downstream of the matrixby separating the flow onto a plurality of “lines,” such as by using aseries of parallel-running conveyors and a diverter (not shown) to routethe articles accordingly. The individual conveyors in these lines maythen form the infeed conveyors of a second matrix system (not shown),which can further sort the articles into even smaller sub-groups. Theprocess may repeat as necessary to create the desired degree or “level”of sortation for a particular operation.

Rather than using a matrix system 10 to deliver articles from a storagelocation, it may find utility in a converse arrangement. For example,upon receiving a delivery, the articles (boxes, packages, etc.)requiring sortation may transfer to an infeed conveyor at the warehousethat ultimately splits into a plurality of the infeed conveyors 12 ofthe matrix system 10. Sortation of the articles may follow as describedabove to place all those with a common parameter or characteristic on aparticular takeaway conveyor 14 for delivery to a particular storagelocation in the warehouse (e.g., one for books on a certain topicreside, books having a title beginning with a particular letter of thealphabet reside, etc.). The takeaway conveyors 14 can then be switchedto infeed conveyors 12 for delivering articles for delivery back to thematrix 10, which would then sort those articles having the commoncharacteristic that triggers transfer to the takeaway conveyors (whichformerly served as infeed conveyors).

In accordance with still another aspect of the invention, the matrixsystem 10 may also include three or more levels of conveyors. Forexample, the third conveyors of this level may receive selected articlesfrom the second takeaway conveyors for delivery to differentdestinations. Alternatively, these third conveyors may serve as secondinfeed conveyors for delivering articles to takeaway conveyors 14 alsocommon to the first infeed conveyors 12, or instead may also receivearticles from the infeed conveyors and thus function as a second set oftakeaway conveyors.

In the latter case, the third conveyors preferably extend parallel tothe second takeaway conveyors 14 and may lie either above or below theinfeed conveyors 12 (with corresponding means, such as chutes or poweredelevators, used to transfer the articles depending on the orientationused). However, the third conveyors preferably run in a directionopposite that of the takeaway conveyors 14 and are associated withdownstream sub-sortation stations (either individuals for placing theobjects in bins, automated sorters for doing so, etc.). This is shown inFIG. 7 by opposing arrows B and C along the takeaway conveyors 14 andthe third conveyors 34, respectively (with arrows A and D also showingthat the infeed conveyors 12 may also run in different directions). Themeans for transferring articles may include a transfer conveyor 16similar to the one described above, but capable of elevating thearticles in a reliable fashion (such as by using a high-frictionsurface, scoops, cleats, a “wedge” conveyor, or similar types ofarrangements that are well known in the art for reliably conveyingarticles against gravity). As perhaps best understood with reference toFIG. 8, it is also preferable for the transfer conveyor 16 to terminatein a plane above the corresponding third conveyor 34, such thattransferred articles simply drop onto the conveying surface.

As should be appreciated, a matrix system 10 with two or more sets oftakeaway conveyors may provide several advantages in use. For example,in the case of two levels of takeaway conveyors 14, 34, the ability totransfer articles from the infeed conveyor 12 to either a second orthird takeaway conveyor 14 or 34 during a single run can significantlyincrease the potential throughput of the system 10. This increaseresults without a corresponding increase in the conveying speed, whichhelps to make the overall operation more relaxed and effective than mostconventional approaches.

Another possibility involves alternating between the two levels oftakeaway conveyors 14, 34 in the matrix sorter system 10. For example,the lower takeaway conveyors 14 used in conjunction with the infeedconveyors 12 may sort a first batch or group of articles introduced tothe system 10. After the articles comprising the first batch move fromthe infeed conveyors 12, a second group of articles (of the same or adifferent type) may be introduced to the system 10 and transferred tothe upper takeaway conveyors 34 while the first group are simultaneouslybeing conveyed and sorted downstream on the lower takeaway conveyors 14.Using such an arrangement may allow for continuous operation of thesystem 10, despite the possible need for periodic downtime with onelevel of takeaway conveyors 14 or 34 after sorting a batch of articles(such as to address mis-sorted articles or situations where one or morearticles are incorrectly introduced into the system and need to bereplaced to fill a particular order).

Still another possible use of a matrix system involves operating only aportion of the infeed conveyors 12 at a given time. For example, in thearrangement shown in FIG. 4, only one of four groups G₁, G₂, G₃, G₄ offive infeed conveyors 12 may deliver articles to the takeaway conveyors14 (or deliver articles from only a certain storage location in awarehouse) during a first shift, with other groups used during differentshifts. This maintains constant wear on the conveyors of the variousgroups and also extends their service life. At times when an increasednumber of articles require sorration (i.e., at Christmas), then allcorresponding infeed conveyors 12 present may run simultaneously.

An alternative means for transferring articles between the conveyors 12,14 may comprise a separately actuatable drop-down portion 36 of theassociated infeed conveyor 12 (see FIGS. 9 and 10, as well as U.S. Pat.No. 4,426,074, the disclosure of which is incorporated herein byreference). Obviously, these drop down portions 36 would be placed at ornear the intersections with the takeaway conveyors 14, which as shouldbe appreciated represent possible or potential transfer points.

In the case of drop down portions 36, offsetting or “staggering” thetransfer points along the lateral extent of the takeaway conveyors 14a-14 d comprising the system 10 prevents collisions among articlestransferred from upstream infeed conveyors (such as infeed conveyors 12a-12 c in the case of four). FIG. 9 illustrates this approach by makingeach second or takeaway conveyor 14 wider than the associated first orinfeed conveyor 12 (note phantom portion), and/or by selectivelypositioning the end of the drop down portion 36. This allows for theeasy and efficient placement of articles at different locations alongthe width of the takeaway conveyor 14, while preventing collisions witharticles delivered from an upstream transfer point associated with adifferent infeed conveyor 12. In other words, the initial location ofeach article upon transfer may be staggered along the lateral dimensionof the associated takeaway conveyor 14. This is illustrated by showingpackages or parcels P₁ and P₂ in a side-by-side configuration in FIG. 10(which shows the actual transfer of the second package or parcel P₂ tothe takeaway conveyor 14 via the delivery end of a “staggered” drop downportion 36).

In accordance with a further aspect of the invention, the means fortransferring at least one article to an intersecting one of the secondconveyors may comprise a transfer conveyor in the form of a transpositorconveyor 38, which may form part of one or more of the first or infeedconveyors 12. Specifically referring to FIGS. 11-12, the transpositorconveyor 38 may include a retractable section 40 that overlies thetakeaway conveyor 14 at each junction or intersection (see, e.g., FIG.18). FIG. 11 illustrates an oversized gap between the moving end of thesection 40 and the corresponding end of the upstream section of conveyor12, which would normally be substantially closed when the transpositorconveyor 38 is extended so as to create a substantially continuousconveying surface.

Thus, if product is to pass through the infeed conveyor 12 and continuealong the conveying path it forms, the retractable section 40 of thetranspositor conveyor 38 remains in the normal or extended condition tocreate a substantially continuous path. However, if it is desired todeliver a approaching product to the adjacent takeaway conveyor 14(which condition of the product may be sensed using a sensor, such as aphotodetector), the section 40 of the transpositor conveyor 38 may beretracted in the conveying direction to expose a second conveyingsurface, such as of the takeaway conveyor 14 or a transfer conveyor 16,and deliver the product thereto. In this manner, the transpositorconveyor 38 may run continuously, so that upstream product continues tomove, while the desired product is reliably delivered for furtherconveyance by the takeaway conveyor 14.

With reference to FIGS. 13-17, an example of a transpositor conveyor 38in accordance with one preferred embodiment is shown. Specifically, theretractable section 40 comprises a moving support bed including a pairof side rails 42. These rails 42 are slidably received in correspondingguides 44 associated with a housing 46 adapted for telescopicallyreceiving the retractable section 40 in the retracted condition. Theguides 44 may be separate structures spaced along depending side framemembers 46 a, 46 b of the housing, which are interconnected by a bed 46c forming a support surface for the articles or products being conveyed.However, the use of a continuous guide is possible.

To move the section 40 to and fro relative to the housing 46, one ormore pinions 48 is associated with a rotatable drive shaft 50, which maybe supported by the side frame members 46 a, 46 b of housing 46. Thepinions 48 interface with elongated racks 52 carried by the retractablesection 40. A corresponding motive device, such as a servomotor 54,serves to rotate the drive shaft 50 to advance or retract the section 40to a nested condition within the housing 46.

An endless belt 56 is provided for conveying articles along thetranspositor conveyor 38. As perhaps best shown in FIG. 15, the belt 56extends over front and rear guide structures of the conveyor 38 tocreate an endless path of travel. Preferably, these guide structurescomprise fixed nose bars 58, 60 positioned at the end of section 40 andhousing 46, respectively, but idler rollers or the like could also beused.

Opposite the conveying path, the belt 56 extends over a first idler 62that is connected to and moves along with the section 40, and thusmaintains a fixed relationship with the forward nose bar 58. The belt 56then extends over a first idler 64 supported by the side frame members46 a, 46 b, and then over a drive shaft 66 for driving the belt 56. Thedrive shaft 66 may include belt-engaging elements, such as sprockets,and is rotatably associated with a second motive device, such as aservomotor 68, operating independent of the first motive device forretracting and extending the section 40 of the transpositor conveyor 38.Pinch rollers 70, 72 are also provided for helping to retain the belt 56in engagement with the driving elements on the drive shaft 66.

Referring now to FIG. 16, the retractable section 40 in the normallyextended condition is shown. In this position, the pinions 48 areadjacent the rearward portion of the racks 52. When used in system 10,the belt 56 may be driven to move the articles along the conveyor 12 inthe conveying direction and along the substantially continuous pathformed.

When it is desired to transfer the articles from the infeed conveyor 12associated with the transpositor conveyor 38, such as to a transferconveyor 16 for delivering the articles to a takeaway conveyor 14, thesection 40 is retracted by activating the motor 54 to rotate the pinions48 in the corresponding direction. This retraction is completed so as tomore fully expose a gap G between the transpositor conveyor 38 and theupstream end of conveyor 12, such that the articles being conveyed maypass. This movement, combined with the combined effects of the forwardmovement of the belt 56, the inertia of the articles, and gravity,serves to deposit the articles on a surface 16 a of the transferconveyor 16 (which as shown may comprise a closely spaced, generallyflat belt conveyor combined with a roller chute type of conveyor thatmay lead to a takeaway conveyor 14, but any other arrangement capable ofconveying away the articles could be used).

However, as shown in FIG. 18, it is possible to provide the transferfunction by simply positioning the transpositor conveyor 38 associatedwith the infeed conveyor 12 at each intersection with a takeawayconveyor 14. In other words, the retractable section 40 is positioneddirectly above and overlying the conveying surface of the takeawayconveyor 14, such that the articles are deposited directly thereon forconveyance in a second direction and thus effecting efficient sortation.

As should be appreciated, the relationship of the idlers 62, 64 is suchthat the section 40 retracts while maintaining the length of the belt 56below the section 40 at a fixed distance relative to the leading edge(i.e., nose bar 58). Despite this retraction of the section 40, movementof the belt 56 in the conveying direction may continue as a result ofthe driving force provided by the second motive device 68.

Once the articles have cleared, as may be estimated based on time or bya suitable sensor, the section 40 may be extended to further thedownstream conveyance of any upstream articles along the associatedconveyor 12. When further sortation is desired by delivering articles tothe takeaway conveyor 14, the section 40 may then again be retracted. Asshould be appreciated, this operation may be repeated as necessary toeffect sortation of the articles in the desired manner.

Preferably, the transpositor conveyor 38 is designed to have a lowprofile, and for this purpose may incorporate Applicant's MICROSPANconveyor chain technology, as described in U.S. Pat. No. 7,314,132, thedisclosure of which is incorporated herein by reference.

The foregoing descriptions of various embodiments of sorter systems andrelated methods provide illustration of the inventive concepts. Thedescriptions are not intended to be exhaustive or to limit the disclosedinvention to the precise form disclosed. Modifications or variations arealso possible in light of the above teachings. For example, theconveyors 12, 14, 16, 34 if comprised of modular links may be providedwith specialized links or rollers to facilitate article transfer (see,e.g., U.S. Pat. No. 6,874,617 to Layne, the disclosure of which isincorporated herein by reference). Also, it should be appreciated thatbooks are mentioned merely to illustrate one possible type of articlecapable of being conveyed or sorted using the disclosed inventions. Theembodiments described above were chosen to provide the best applicationto thereby enable one of ordinary skill in the art to utilize theinventions in various embodiments and with various modifications as aresuited to the particular use contemplated (such as, again, for conveyingor sorting articles other than books). All such modifications andvariations are within the scope of the invention.

The invention claimed is:
 1. A conveyor system for intended use inconjunction with the sorting of articles, comprising: a plurality offirst substantially continuous conveyors extending in a first direction,each providing a first continuous, uninterrupted conveying surface forthe articles; a plurality of second substantially continuous conveyorsextending in a second direction and intersecting the first conveyors,each second conveyor providing a second conveying surface for anyarticles transferred from one or more of the intersecting firstconveyors; and means for transferring at least one article from at leastone of the first conveyors to an intersecting one of the secondconveyors, said means comprising at least a portion of the firstconveying surface.
 2. The conveyor system according to claim 1, whereinthe means for transferring comprises a transpositor conveyor.
 3. Theconveyor system according to claim 2, wherein the transpositor conveyoroverlies the second conveying surface of at least one second conveyor.4. The conveyor system according to claim 2, wherein the transpositorconveyor comprises a retractable conveying surface.
 5. The conveyorsystem according to claim 4, wherein the retractable conveying surfaceis positioned at least partially within a housing of the transpositorconveyor in a retracted condition.
 6. The conveyor system according toclaim 1, wherein the means for transferring comprises a conveyor sectionselectively moveable from a first position allowing conveyance of thearticles along at least one of the first conveyors to a second positionallowing transfer of the articles to at least one of the secondconveyors.
 7. The conveyor system according to claim 1, wherein thefirst and second conveyors comprise substantially continuous endlessbelt or chain conveyors.
 8. A conveyor system for intended use inconjunction with the sorting of articles, comprising: a plurality offirst substantially continuous conveyors extending in a first direction,each providing a first continuous, uninterrupted conveying surfacedefining a first path of travel in the first direction for the articles;a plurality of second substantially continuous conveyors extending in asecond direction and intersecting the first conveyors, each secondconveyor providing a second conveying surface; and a transfer conveyorfor transferring articles from the first conveying surface of at leastone of the first conveyors to the second conveying surface of at leastone of the second conveyors, said transfer conveyor at least partiallydefining the first path of travel.
 9. The conveyor system according toclaim 8, wherein the transfer conveyor comprises a transpositorconveyor.
 10. The conveyor system according to claim 9, wherein thetranspositor conveyor forms a part of the first conveying surface of theat least one first conveyor.
 11. The conveyor system according to claim8, wherein the transfer conveyor comprises a drop-down section of the atleast one first conveyor.
 12. A conveyor system for intended use inconjunction with the sorting of articles, comprising: a plurality offirst substantially continuous conveyors extending in a first direction,each providing a first continuous, uninterrupted conveying surface forthe articles; a plurality of second substantially continuous conveyorsextending in a second direction and intersecting the first conveyors,each second conveyor providing a second conveying surface; and atranspositor conveyor for transferring articles from the first conveyingsurface of at least one of the first conveyors to the second conveyingsurface of at least one of the second conveyors, at least a portion ofthe transpositor conveyor comprising a portion of the first conveyingsurface.
 13. The conveyor system according to claim 12, wherein thetranspositor conveyor overlies the second conveying surface of the atleast one second conveyor.
 14. The conveyor system according to claim12, wherein the transpositor conveyor comprises a retractable conveyingsurface.
 15. The conveyor system according to claim 14, wherein theretractable conveying surface is positioned at least partially within ahousing of the transpositor conveyor in a retracted condition.
 16. Theconveyor system according to claim 12, further including a transferconveyor for transferring articles from the at least one first conveyorto the at least one second conveyor.
 17. The conveyor system accordingto claim 12, further including a transpositor at each intersectionbetween a first conveyor and second conveyor.
 18. The conveyor system ofclaim 8, wherein the transfer conveyor is selectively moveable from afirst position allowing the articles to travel along at least one of thefirst paths to a second position diverting articles to at least one ofthe second conveying surfaces.